"The main goal is to find out the root cause," said James Wiggins, a spokesman for the U.S. Pipeline and Hazardous Materials Safety Administration. The answer could prevent future pipeline ruptures, he said.

A plan submitted by BP to federal regulators said the pipe will be cut into smaller pieces for study of corroded spots, sediment buildup and scaly deposits, which are thought to have contributed to the corrosion outbreak.

The whole operation is expected to start on Thursday and take four days. Federal pipeline regulators will be on hand to "witness the activities," according to the correspondence.

BP spokesman Daren Beaudo said the company is cooperating fully in handing over the pipe section to regulators.

"They said they wanted it and we said we'd do it," he said. "We're all interested in the corrosion mechanism."

The badly corroded, above-ground pipeline has been out of service since it leaked in August, and BP plans to demolish it.

BP runs Prudhoe Bay on behalf of itself and other owners, including Exxon Mobil and Conoco Phillips.

The problem pipes carry oil from the vast field to the larger trans-Alaska pipeline, which carries the crude to Valdez.